The Journey of a Drop of Urine: From Blood to Flush

Blood enters the kidneys loaded with waste and excess water.
In the nephrons, waste is filtered while nutrients are reclaimed.
The purified blood flows back to circulation, while waste becomes urine.
Urine trickles into the renal pelvis before entering the ureters.
Smooth muscles in the ureters push urine toward the bladder.
The bladder expands like a balloon as it fills.
When full, nerve signals tell the brain it’s time to go.
The urethra opens, releasing stored urine in a quick, coordinated flow.
Each flush represents hours of microscopic kidney labor.
The whole journey—from blood to flush—takes only a few hours.